As a novice to this forum when I read the cataracts thread I foolishly :o argued that they wouldn't have used PVA to bond the safety glass because PVA is water soluble which would cause problems.

Since they really did use PVA the water bath removal makes sense.

If you dig through the old threads you will read my experience with water. It was positive. I tried it with the "green" type used by Zenith and others, the one that does not respond well to heat. I bought a cheap blow-up kiddie pool at the dollar store and let the crt sit face down in water. It took about 5 days, as I recall. I think the longer you wait the easier it will go. I tried it later with the RCA style PVA and it didn't respond at all even after a week. If you have an outbuilding with some spare room, I say just get such a pool and let it soak. Detergent couldn't hurt. Some have suggested kerosene or other solvents-the trouble I see there is that you then have to deal with this vat of flammable, smelly stuff. There is a product called Bean-a-Doo which is sold as a soaking agent to remove adhesives from automotive trim, and perhaps it would work. Made from soybean oil. But, very expensive. Even plain vegatable oil would be expensive if you bought enough to soak a tube.

I have removed several faceplates with heat, with good results, but I am nervous after reading some of these experiences. I may be removing one this week but I don't think that one has any adhesion left at all. I may stick with water from here on out.

I've posted this before, but here it is again:
My only "serious" experience occurred the summer when I was 17. I was helping my Dad swap CRTs (25AXP22's) between two sets at his TV shop. I pulled the bad CRT out of the set and set it on the dump pile outside, then busted the "tit" to let it go to air, no problem. Dad, meanwhile, left to go get a new blue lateral assembly at the parts place a mile away. I was alone and with the vigor of youth, decided to pull the "good" tube to have it ready when Dad got back. I unbolted it just fine, and I lifted it from the set (by the neck) and set it on the edge of the cabinet to reposition it. I then hoisted it up by the sides (face down), only to have the 2nd anode button come in contact with my abdomen and now-sweaty t-shirt. WHAM!! - I got the residual charge. I reacted by pushing it away from me, into the corner of a workbench, imploding the CRT about 6-8" from me. I was shaking, and alone, and uninjured. My only scare was what was I going to tell Dad when he returned. Thankfully, he laughed it off after ensuring I wasn't hurt. Glass shards were everywhere, and we even found some 6 months later when we moved some equipment around in the shop.

Cheers,

Have you considered trying biodiesel? B100 should cost around $3.50 a gallon, and is not that flammable or smelly. It dissolves rubber fuel lines, it might work well on this. The only trouble would be finding it as very few fuel stations sell 100% biodiesel, moreso this time of year.

-J

Well, there's brake fluid, which is widely known to dissolve paint. maybe it would do a CRT. My brother uses brake fluid to remove the paint off of his plastic model train models.

If the bonding material on a particular tube is a type of polyester resin (I believe that some were ... PPG 5252 or something like that), methylene chloride will do the job. Very nasty, however. :yuck:

jr

Dow Chemical's formula is in Patent 3007833:

33 parts by weight diglycidyl etherr of bisphenol A, 67 parts diglycidyl ether of polyoxypropylene glycol having a molecular weight of 400 and 5.5 parts of monoethanolamine and 1 part of diethylenetriamine.

What that means, I dunno. The patent is for the use of a Saran wrap band around the tube and safety plate while filling the gap with the above mix.

US Patent 3265234 from Union Carbide lists a number of other chemicals that were used to bond the safety plates - about 4 or 5 formulations are compared.

I guess not all CRT's used the same bonding materials....


Cheers,

YES! I think that is the reason for some frustration on this board... methods for dealing with one type of bonding material may not be effective, and perhaps even dangerous to use to remove another type.
Dow Corning 184 for example, was sometimes used on smaller special purpose tubes where high optical quality was desired... I suspect that heat alone would not be effective to remove a faceplate bonded with 184.
jr

Really nasty and dangerous. It has a high vapor pressure and will evaporate very quickly. It would have to be a very valuable tube before I'd try it.

I'm not sure how you'd do that either. I still have a scar from trying to remove a PMT from a light guide that we wanted to save that had been bonded with Dow 184. Have you ever seen a cataract or similar form with 184? I'd expect it to last nearly forever. Rebuilding a CRT bonded with it would be a real bear. A long term soak in trichloroethylene would swell the 184 and loosen the bond, but is also hazardous.

Dow 184 is nearly ideal for the purpose, but would break the bank for a large CRT.

Yes, I have observed partial de-lamination on some tubes using 184.... sort of looked like "worm tracks" in the material.

I see that Amazon has the material listed, wonder how many 21" crts could be bonded with an 3.9kg "kit" for $336 ?:eek:

jr

Guess it would depend on the bond line. If it was 1/8" you could do about five 21" CRTs.

John

Used to put old CRTs in a 55 gal trash barrel & chuck a rock in from about 20' away. Always got an impressive geyser of glass out of the barrel.

Furniture Blanket
 

My Dad owned a TV shop ,we wrapped a furniture moving blanket around the tube: Then , put it in a METAL trashed can and then broke the neck off with a LONG pipe.
Now working at NASA with huge vacuum chambers on night-shift..............
Put it this way........... I don't fall asleep at work !!!
I'm always ready for the unexpected !!!!!!!!!!!!!!!!!:scratch2::smoke::nono:

And the neighbors might think that you have set up a meth lab... :D

Working in a tube rebuilding facility in the '60's, the only time we had a tube implode was in the ovens. Years ago, I had a TV repair shop in our local flea market where I would repair TV's while you wait. There was another guy who started up on the other side of the market which we called "Brand X". A good guy but more of a piddler. One day I heard a tube go off (I knew that sound!) and ran to the other side of the market where he was sitting down on the floor in bewilderment beside the TV. I was for sure at that point that he was seriously hurt as there were chunks of glass shards all over the place and a few customers running. What he had done was cut the pressure band off of a live 25" tube to make it fit into the cabinet. DON'T YOU EVER CUT A PRESSURE BAND OFF OF A LIVE TUBE!!! EVER!!!

The theory is before a tube can implode, the faceplate has to be forced inward and it cannot if there is a band on the tube. For rebuilding, we took the band off after the tube was let down to atmosphere pressure.